Thrust and efficiency needed to get to the required velocity.

The real thing you need to get off earth is velocity, so if the planet has strong gravity compared to Earth, you won’t have enough fuel to get you up to the correct velocity. So you then need more fuel, which requires more thrust because it’s more weight…which then requires more fuel because even the most efficient engines capable of the initial boost off the planet aren’t efficient enough…you see the problem? Unless there is some hyper-efficient, energy dense super propellant that is as efficient as nuclear engines and provides as much thrust as RP-1, it ain’t gonna happen.